Master Spindle for Tapping Machine

ABSTRACT

Disclosed is a master spindle for tapping machine. The master spindle comprises a chuck ( 53 ) having a tap ( 51 ) detachably mounted thereto; a chuck support member ( 55 ) having the chuck ( 53 ) mounted thereto; a spindle bolt ( 57 ) fastened to the chuck support member ( 55 ) at an upper end thereof; and a bushing nut ( 59 ) threadedly coupled to the spindle bolt ( 57 ) and positioned below the chuck support member ( 55 ). The chuck support member ( 55 ) has an upper end to which the chuck ( 53 ) is mounted and a lower end to which the spindle bolt ( 57 ) is fastened, the upper and lower ends being integrally formed with each other.

The present invention relates, in general, to a master spindle for atapping machine which can tap a female thread in a workpiece at highspeed and with high precision, and, more particularly, to a masterspindle for a tapping machine in which a single chuck support member isused, an umbrella-shaped chip cover or a fluctuation correcting cap isselectively fitted around the chuck support member, the chuck supportmember is defined with a tap separation hole for easy separation of atap from a chuck, and tapped holes are defined in a bushing nutthreadedly coupled to a spindle bolt.

BACKGROUND ART

Referring to FIG. 1, in a conventional master spindle 1 for a tappingmachine, a tap 3 is detachably mounted to a chuck 5 which is mounted toan upper chuck support member 7. The upper chuck support member 7 isdetachably locked to a lower support member 9 which is mounted to aspindle bolt 11. A bushing nut 13 is locked to the spindle bolt 11 andis positioned below the lower support member 9. Therefore, the spindlebolt 11 can be raised and lowered while being rotated relative to thebushing nut 13 fastened to a jig 15. The lower end of the spindle bolt11 is connected to a universal joint (or a cable) (not shown) to receivepower.

DISCLOSURE OF INVENTION Technical Problem

However, in the conventional master spindle 1 for a tapping machine,since the upper chuck support member 7 and the lower support member 9are bolted to each other so that only the lower support member 9 and thespindle bolt 11 need be replaced with new ones when the spindle bolt 11is broken, problems always occur due to non-concentricity between theupper chuck support member 7 and the lower support member 9. Also, dueto the fact that the upper chuck support member 7 and the lower supportmember 9 are bolted to each other, the length ‘h’ of an entire supportstructure including the upper chuck support member 7 and the lowersupport member 9 increases. In this regard, while a defect is caused inthat the tap 3 fluctuates when tapping a workpiece, means for preventingthe fluctuation of the tap 3 has not been disclosed so far in the art.

Further, in the conventional master spindle 1 for a tapping machine, ascan be readily seen from FIG. 2, when tapping is conducted in a verticaldirection, chip particles 17 are likely to be introduced into the chuck5, whereby the tap 3 may not be easily separated from the chuck 5 due tothe presence of the chip particles 17. Also, while conducting tappingwork in the vertical direction, the chip particles 17 are likely toenter a gap between the bushing nut 3 and the spindle bolt 11, wherebythe screw threads of the spindle bolt 11 and the bushing nut 13 can becrushed.

In addition, in the conventional master spindle 1 for a tapping machine,as can be readily seen from FIG. 3, due to the fact that a flangeportion 13 a of the bushing nut 13 is defined with only two mountingholes 13 b, the jig 15 must be located under the flange portion 13 a ofthe bushing nut 13 as shown in FIG. 2. Therefore, in case that the jig15 must be located over the flange portion 13 a of the bushing nut 13,since the bushing nut 13 cannot be fastened to the jig 15, it isimpossible to implement the tapping work.

Technical Solution

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a master spindle for a tapping machine in whicha single chuck support member for supporting a chuck is used to decreasethe length of a chuck support structure and solve the drawbacksresulting from non-concentricity of the chuck support structure.

Another object of the present invention is to provide a master spindlefor a tapping machine in which an umbrella-shaped chip cover is fittedaround the lower end of a chuck support member to prevent chip particlesfrom entering a gap between a bushing nut and a spindle bolt and avoidbreakage of screw threads of the bushing nut and the spindle bolt.

A further object of the present invention is to provide a master spindlefor a tapping machine in which a fluctuation correcting cap fittedaround a chuck support member is coupled to a bushing nut by bolts sothat, when a spindle bolt threadedly coupled to the bushing nut isrotated relative to the bushing nut, the chuck support member connectedintegrally to the spindle bolt can be raised and lowered, withoutfluctuating, on the circumferential inner surface of the fluctuationcorrecting cap, and so that the fluctuation correcting cap can preventchip particles from entering a gap between the bushing nut and thespindle bolt.

Yet another object of the present invention is to provide a masterspindle for a tapping machine in which a chuck support member is definedwith a tap separation hole for easy separation of a tap from a chuck sothat, even when chip particles are introduced into the chuck whiletapping is implemented in a vertical direction, since it is possible topush the lower end of the tap out of the chuck by a lever insertedthrough the tap separation hole, the tap can be reliably separated fromthe chuck as the occasion demands.

Still another object of the present invention is to provide a masterspindle for a tapping machine in which auxiliary mounting holes aredefined in a flange portion of a bushing nut so that the bushing nut canbe mounted to a jig irrespective of the position of the jig.

ADVANTAGEOUS EFFECTS

As apparent from the above description, the master spindle for a tappingmachine according to the present invention provides advantages in that,since a chuck support member has integral upper and lower ends,drawbacks due to non-concentricity of a chuck support structure in theconventional master spindle can be eliminated, and the length of theentire chuck support structure can be decreased, whereby the fluctuationof the master spindle during tapping is lessened and the precision oftapping work is improved.

Also, in the master spindle for a tapping machine according to thepresent invention, due to the presence of an umbrella-shaped chip cover,it is possible to prevent chip particles from entering the gap between abushing nut and a spindle bolt and avoid the breakage of screw threadsof the bushing nut and the spindle bolt.

Further, in the master spindle for a tapping machine according to thepresent invention, by the fact that the chuck support member is definedwith a tap separation hole for easy separation of a tap from a chuck,even when chip particles are introduced into the chuck while tappingwork is implemented in a vertical direction, it is possible to push thelower end of the tap out of the chuck by a lever inserted through thetap separation hole, whereby the tap can be reliably separated from thechuck as the occasion demands.

Moreover, in the master spindle for a tapping machine according to thepresent invention, because tapped holes are defined in a flange portionof the bushing nut, the bushing nut can be mounted to a jig irrespectiveof the position of the jig.

Furthermore, in the master spindle for a tapping machine according tothe present invention, due to the fact that a fluctuation correcting capcan lessen the fluctuation of a spindle body, even when the screwthreads of the bushing nut and the spindle bolt are abraded, the tappingwork can be reliably implemented. Also, it is possible to extend theservice lives of the bushing nut and the spindle bolt and prevent chipparticles generated during tapping from entering the gap between thebushing nut and the spindle bolt.

Although the preferred embodiment of the present invention has beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

DESCRIPTION OF DRAWINGS

The above objects, and other features and advantages of the presentinvention will become more apparent after a reading of the followingdetailed description when taken in conjunction with the drawings, inwhich:

FIG. 1 is a half sectional view illustrating a conventional masterspindle for a tapping machine;

FIG. 2 is a half sectional view illustrating the master spindle of FIG.1 in a state in which tapping is implemented in a vertical direction;

FIG. 3 is a perspective view independently illustrating the bushing nutshown in FIGS. 1 and 2;

FIG. 4 is a half sectional view illustrating a master spindle for atapping machine in accordance with an embodiment of the presentinvention;

FIG. 5 is a half sectional view illustrating the master spindle of FIG.4 in a state in which tapping is implemented in a vertical direction;

FIG. 6 is a half sectional view illustrating the master spindleaccording to the present invention, with a fluctuation correcting capfitted around a chuck support member;

FIG. 7 is a half sectional view independently illustrating thefluctuation correcting cap;

FIG. 8 is a perspective view illustrating a bushing nut; and

FIG. 9 is a half sectional view illustrating the master spindle with thebushing nut mounted to a jig placed on a flange portion of the bushingnut.

BEST MODE

Reference will now be made in greater detail to a preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings. Wherever possible, the same reference numerals will be usedthroughout the drawings and the description to refer to the same or likeparts.

Referring to FIG. 4, a master spindle 50 for a tapping machine inaccordance with an embodiment of the present invention comprises a chuck53 having a tap 51 detachably mounted thereto; a chuck support member 55having the chuck 53 mounted thereto; a spindle bolt 57 fastened to thechuck support member 55 at an upper end thereof; and a bushing nut 59threadedly coupled to the spindle bolt 57 and positioned below the chucksupport member 55.

The chuck support member 55 has an upper end to which the chuck 53 ismounted and a lower end to which the spindle bolt 57 is fastened. Theupper and lower ends of the chuck support member 55 are integrallyformed with each other. By this fact, the strength of the screw threadsof the spindle bolt 57 can be improved, and, as will be described laterin detail, it is possible to prevent chip particles 100 from enteringthe gap between the spindle bolt 57 and the bushing nut 59. As aconsequence, because the spindle bolt 57 can be used semi-permanently,it is not necessary to employ two separate support members as in theconventional art.

Also, due to the fact that the chuck support member 55 has integralupper and lower ends, the drawbacks provoked due to non-concentricity ofa chuck support structure in the conventional master spindle can beovercome, and the length ‘S’ of the entire chuck support structure canbe decreased, whereby the fluctuation of the master spindle 50 duringtapping is lessened and the precision of tapping work is improved.

Referring to FIG. 5, an umbrella-shaped chip cover 61 is provided to thelower end of the chuck support member 55. The chip cover 61 preventschip particles 100 which are generated from a workpiece (not shown),from entering the space between the spindle bolt 57 and the bushing nut59, even when tapping work is implemented in a vertical direction, sothat it is possible to prevent the screw threads of the spindle bolt 57and the bushing nut 59 from being crushed.

Referring to FIG. 6, in a more developed form, in order to prevent thechip particles 100 from entering the space between the spindle bolt 57and the bushing nut 59 and to prevent the tap 51 from fluctuating, thechuck support member 55 is provided with a fluctuation correcting cap70.

The fluctuation correcting cap 70 is defined with an opening 77 intowhich the chuck support member 55 is fitted so that a circumferentialouter surface of the chuck support member 55 is brought into tightcontact with a circumferential inner surface 79 of the fluctuationcorrecting cap 70. The fluctuation correcting cap 70 has a flangeportion 75 which is coupled to the bushing nut 59 by locking bolts 81.

Consequently, when the spindle bolt 57 is rotated relative to thebushing nut 59 which is fastened to a jig 91, the chuck support member55 which is integrally coupled to the spindle bolt 57 is brought intotight contact with the circumferential inner surface 79 of thefluctuation correcting cap 70 and can be raised and lowered withoutfluctuating relative to the fluctuation correcting cap 70 fastened tothe bushing nut 59. Also, the fluctuation correcting cap 70 functions toprevent the chip particles 100 from entering the space between thespindle bolt 57 and the bushing nut 59.

Referring to FIG. 7, the fluctuation correcting cap 70 has a cylindricalconfiguration similar to the chuck support member 55. An O-ring 71 isfitted in the circumferential inner surface 79 of the fluctuationcorrecting cap 70 adjacent to the upper end of the fluctuationcorrecting cap 70. An oil inlet hole 73 is defined through thefluctuation correcting cap 70 and communicates with the opening 77.

The O-ring 71 serves to occupy a gap between the chuck support member 55and the fluctuation correcting cap 70, so that, when the chuck supportmember 55 is raised and lowered relative to the fluctuation correctingcap 70, the fluctuation of the chuck support member 55 can be furtherlessened.

The oil which flows into the fluctuation correcting cap 70 through theoil inlet hole 75 reduces friction when the chuck support member 55 isrotated relative to the fluctuation correcting cap 70.

Due to the presence of the fluctuation correcting cap 70 constructed asmentioned above, even when the screw threads of the spindle bolt 57 andthe bushing nut 59 are crushed, since the chuck support member 55 slidesin the fluctuation correcting cap 70 without fluctuating, the tap 51 isprevented from fluctuating, whereby the tapping work can be reliablyimplemented and the chip particles 100 generated during implementationof the tapping work can be prevented from entering the space between thespindle bolt 57 and the bushing nut 59.

Referring to FIGS. 4 and 5 again, the chuck support member 55 is definedbelow the chuck 53, with a tap separation hole 63 for easy separation ofthe tap 51 from the chuck 53. Hence, when the tapping work isimplemented in the vertical direction, if the chip particles 100 areintroduced into the chuck 53 and impede easy separation of the tap 51from the chuck 53, by inserting a lever (not shown) or the like into thetap separation hole 63 to push the lower end of the tap 51 out of thechuck 53, the tap 51 can be easily separated from the chuck 53.

Referring to FIG. 8, the bushing nut 59 is defined with mounting holes59 b and auxiliary mounting holes 59 c. Therefore, as can be readilyseen from FIG. 5, in the case in which the jig 91 is located under aflange portion 59 a of the bushing nut 59, bolts 83 can pass through themounting holes 59 b and be locked into auxiliary mounting holes 93 b ofthe jig 91 to fasten the bushing nut 59 to the jig 91. At this time, asshown in FIG. 6, as the locking bolts 81 are locked into the mountingholes 95 b, the fluctuation correcting cap 70 is fastened to the bushingnut 59. Further, in the case in which the jig 91 is located over theflange portion 59 a of the bushing nut 59, as bolts 87 pass throughmounting holes 93 c of the jig 91 and are locked into the auxiliarymounting holes 59 c defined in the flange portion 59 a, the bushing nut59 can be fastened to the jig 91. At this time, as the locking bolts 81are locked into the auxiliary mounting holes 59 c, the fluctuationcorrecting cap 70 is fastened to the bushing nut 59. Hence, the mountingholes 59 b and the auxiliary mounting holes 59 c of the bushing nut 59allow the bushing nut 59 to be fastened to the jig 91 irrespective ofthe location of the jig 91.

1. A master spindle for a tapping machine, comprising: a chuck having atap detachably mounted thereto; a chuck support member having the chuckmounted thereto; a spindle bolt fastened to the chuck support member atan upper end thereof; and a bushing nut threadedly coupled to thespindle bolt and positioned below the chuck support member; wherein thechuck support member has an upper end to which the chuck is mounted anda lower end to which the spindle bolt is fastened, the upper and lowerends being integrally formed with each other.
 2. The master spindleaccording to claim 1, wherein the chuck support member has a lengthwhich is less than that of a conventional chuck support member.
 3. Themaster spindle according to claim 1, wherein an umbrella-shaped chipcover is provided to the lower end of the chuck support member.
 4. Themaster spindle according to claim 1, wherein the chuck support member isprovided with a fluctuation correcting cap.
 5. The master spindleaccording to claim 4, wherein the fluctuation correcting cap is definedwith an opening into which the chuck support member is fitted so that acircumferential outer surface of the chuck support member is broughtinto tight contact with a circumferential inner surface of thefluctuation correcting cap, and has a flange portion which is coupled tothe bushing nut by bolts; and wherein an O-ring is fitted in thecircumferential inner surface of the fluctuation correcting cap adjacentto an upper end of the fluctuation correcting cap, and an oil inlet holeis defined through the fluctuation correcting cap to communicate withthe opening.
 6. The master spindle according to claim 1, wherein thechuck support member is defined, below the chuck, with a tap separationhole for easy separation of the tap from the chuck.
 7. The masterspindle according to claim 1, wherein the bushing nut has a flangeportion which is defined with mounting holes and auxiliary mountingholes.